Furnace construction



Jan. 9,- 1945, E'. DOLEZAL- ET AL FURNACE CONSTRUCTION Filgd Aug. 10,. 1942 2 Sheets-Sheet -1 VELTON v HUBBY LOUIS J. WEBER I v EDWARD DOLEZAL INVENTORS I BY Y ORN s structure.

Patented Jan. 9', 1945 1 FURNACE CONSTRUCTION- Edward Doleaal, Louis Joe Weber, and Velton Virgle Hubby, Bartlesville, kla., assignors to. Phillips Petroleum Company, a corporation of Delaware Application August 10, 1942, Serial No.'454,338

9 Claims.

Our invention relates to an improved furnace -More particularly, it relates to an improved arrangement of tube sheets and mountings therefor in a petroleum cracking furnace.

Furnaces of the class to which our improvements relate are customarily built with continuous or one-piece tube sheets for supporting the several banks of tubes. 'Due to .the extreme range of temperatures encountered by the furnace and its many elements, the distortion or buckling of tube sheets and of the tubes themselves has been a considerable source of expense and inconvenience in the operation and maintenance of such furnaces.

,ually and in all directions without the imposition or transfer of stresses from one tube sheet'to another, or from the several sheets to the supporting structure of the furnace.

It is an object of our invention to provide a furnace structure in which the effects of varying temperatures upon the tube supporting structure are minimized to the greatest possible de- Eree.

It is further an object to provide a furnace structure wherein repairs to any given group of tubes may be made with a minimum of disturbance of the other tubes and related structure in the furnace.

A yet further object is to provide a furnace structure which is easily erected and dismantled.

Other objects and advantages will be recognizable by those versed in the art in considering the following specification and the drawings forming a part thereof.

Figure 1 is a partial sectional view of a typical furnace of the class to which our improvements are related.

Figure 2 is an enlarged and more detailed view of a part of the structure illustrated in Figure 1.

Figure 3 is an enlarged sectional view taken about the line 3--3 of Figure 2.

Figure 4 is an enlarged sectional view taken about line l of Figure 1.

line 5- 5 of of which may be fabricated from i-beams, channels or other conventional structural shapes. The roof portion also has complementary stringers l4, preferably-of 2 section (see Figure 4). Suitably suspended from this framework, in a manner to be more fully described, are vertical tube-supporting sheets l5- and inclined tube sheets I6 in the wall and roofseotions, respectively. These sheets are ordinarily constructed of special heat-resisting alloy castings and are provided with openings II to accommodate the tubes which make up the heating coil of the fur nace (tubes not shown). It is desirable to provide an elongated portion l8 projecting from the periphery of the openings in an axial direction, so that ample bearing surface will be provided between the tubes and the openings in which they are supported. Along two parallel edges of each tube sheet is provided a T-fiange portion l9, which serves to reinforce the sheet so that the sheets may be relatively thin and light in weight, yet will have great mechanical strength and resistance to buckling. or warping. These flanges also are utilized to suspend certain of the sheets in a manner to be described later.

Referring particularly to Figures 2 and 3, one

manner of mounting the vertical sheets will be described. To the uprights Ill, H are secured suitable support clips or brackets 20, which may ,provided on the side or vertical edges of the sheet. The top and bottom edges are not flanged, but the bottom edge only of each sheet is, however, provided with an offset 22, so that the adjacent edges of any given pair of sheets will overlap, as shown in Figure 5.

Guide pieces 23 are suitably attached to the upright framework, as shown in Figure 3. After the tube sheets are set into place on support clips 20 and against guide pieces 23, retainer strips 24 are bolted in place to secure the sheets as shown in Figure 3. It will be noted that space is left between the flanges l9 and the guides 23 so that the tube sheet is free to expand in a horizontal direction without imposing a distorting 0 load on any part of the structure. The offsets 22 are so proportioned that vertical expansion of the sheets is permitted likewise.

The inclined tube sheets It in the roof section of the furnace have reinforcing flanges l and onsets 22 like those on the vertical sheets ll except that in the instant case, the flanges are provided on top and bottom edges of the sheet, and the onset portion is formed on one vertical edge of each sheet. The sheets are suspended by the flange on their upper edges, as shown in Figure 4. In that figure, the roof beam. l2 is seen to be fitted with sheet support clips 25,, 25, which are secured in a position such that.

the lower of flanges 19 comes forward of the stringer l4, and overlaps thereon as shown. Support 25 may be secured permanently, if desired. The outward clip 25, however, is secured removably, preferably with bolts. The installation of these roof-section sheets is made by engaging the upper flange of the sheet with the clip 25,

after which the outer clip 26 is bolted in place. A retainer strip 21 is then bolted as shown to secure the bottom'edge of the sheet. It will be tube sheet neiwould be required to time the "whole weight of the tier in compression, with a consequent'great tendency to buckle the sheet tier by its own weight at high temperatures. All of these'disadvantages are avoided by our individually suspended tube sheet structure.

It is likewise obvious from the foregoing description that the details of the supporting and retaining members, and the details of the tube noted that members It and are continuous throughout the span of the inclined roof section, whereas members 26. and 21 are providedin multiple, one each of the respective latter members being provided for each tube sheet. The

same general statement applies to the vertical section, guides 23 being continuous and retainer strips 24 being supplied inmultiple (see Figure 1 also).

From the foregoing description of a desirable embodiment of our invention, it is clear that the construction thereby provided is well suited to the required service. The tube supporting sheets are all suspended individually and can expand freely in any and all directions without transmitting strains to the furnace frame proper. The overlapping ofiset edges permit expansion of the individual sheets without transmitting strain from one to another, yet a substantially continuous closure is provided to prevent undue escape of high temperature gases from the space only permits extreme freedom of expansion be tween adjacent sheets, but actually reduces the total distortion of the upper tubes due to tube sheet expansion. With the sheets individually supported as shown and described, the maximum displacement of tubes will amount in magnitude to the total increase of height of a single sheet. If the tubes were mounted in a single large sheet or in a plurality of smaller sheets stacked edge-. to-edge so that each sheet were supported by those below it, the topmost tube in a bank would be subjected to a displacement equal to the sum ofthe vertical expansions of the individual sheets,

or of the continuous large sheet as the case might be. If the single large sheet or the uppermost sheet of a stacked tier of sheets were restrained at the top, the restraining framework would be stressed ,by the cumulative expansion of the whole sheet or of the several stacked sheets. A further disadvantage of a stacked sheet construction or ofa single floating sheet would be embodied in the fact that the lower portion of the sheets as well are adaptable to many variations or alternatives of design without departing from the scope of our invention.

We claim:

,1. In a. furnace of the class described having a tier of heating tubes supported therein, a multiple tube sheet structure comprising a plurality of tube sheets coextensive with a wall oi the fur nace, said tube sheets being individually suepended and substantially in a common plane, guide members in the framework of said furnace for retaining the several sheets in co-planar re lationship each with the other, and oflset portions formed on an edge of each of said tube sheets whereby overlapping continuity is obtained between the several sheets together with freedom of relative movement therebetween, the sheets forming a partition preventing the passage of any substantial amount of high temperature gas therethrough.

2. A furnace structure including tube supporting framework, vertical guide members secured to the framework, a plurality of contiguous tube supporting sheets coextensive with the guide members, each sheet being individually supported by the framework and in overlapping relationship, one to the'other, the sheets forming a partition preventing the passage of any substantial amount V of high temperature gas therethrough.

3. A furnace structure including tube support ing framework, vertical guide members secured to the framework, a plurality of contiguous tube supporting sheets coextensive with the guide members, each sheet being individually supported by the framework and in overlapping relationship, one to the other, and a plurality of retaining members in association with said guide members, the sheets forming a partition preventing the passage of any substantial amount of high to rperature gas therethrough.

4. A furnace structure including tube supporting framework, vertical guide members secured to the framework, a plurality of contiguous tube supporting sheets coextensive with the guide members, each sheet being individually supported by the framework and in overlapping relation ship, one to the other; and a plurality of retaining members retaining the tube sheets in place, there being at least one of said retaining mom bers engaging each respective one and only one of said tube supporting sheets in association with said guide members so that each of said tube sheets is individually removable from the supporting structure.

5.- A furnace structure including tube supportmg frame members, a plurality of contiguous vertical tube supporting sheets, each being individually supported by the frame members and in overlapping relationship one to the other, a roof member, a plurality of contiguous tube supporting sheets suspended from said roof member and in overlapping relationship one to the other, and forming a continuation of said vertical tube supporting sheet, the sheets forming a partition preventing the passage of any substantial amount of high temperature gas therethrough,

6. In a furnace of the class described, a tube supporting structure comprising in combination a pair of frame members, spaced sets of supporting elements on the frame members projecting .into the space. between the frame members, tube sheets, each one of the tube sheets being supported on a separate spaced set of the supporting elements, and retaining strips secured to the frame members for retaining the tube sheets on the supporting elements and between the frame members.

'1. The combination set forth in claim 6 m ing into the space between the frame members,

' tube sheets, each one of the tube sheets being supported on a separate set of thesupporting elements, and, retaining members removably secured to the frame members for retaining the tube sheets on the supporting elements and between the frame members, there being at least one of said retaining members engaging each respecwhich the tube sheets overlap each other, and

the tube sheets, frame members, and retaining strips are so disposed so as to form a partition which prevents substantial circulation of hot gases therethrough, whereby the sheets are somewhat protected from circulating hot gases.

8. In a furnace of the class described, a tube supporting structure comprising in combination a pair of frame members, spaced sets of supporting elements on the frame members projecti therethrough, whereby the sheets are somewhat protected from circulating hot gases.

EDWARD DOLEZAL. LOUIS JOE WEBER. VELTON VIRGLE HUBBY. 

